The present invention relates to the field of adaptive or mean level detection of targets in nonstationary clutter. Among these techniques are those which use a detection threshold that is determined from estimates of the mean level of clutter plus noise. The primary objective of mean level techniques is to provide a constant false-alarm rate (CFAR) while maintaining detection probabilities for signals of interest. Other techniques that have been used in the past are: tapped delay lines wherein the waveform presenting the data of interest is delayed and summed in such a fashion as to provide an empirical average of the background and use of a passive or active (non-recursive) electronic filter to provide an estimate of the mean level as well as various nonparametric and distribution-free statisical methods described in the literature. The many CFAR techniques have varying degrees of complexity of implementation and their performance also varies considerably depending on the actual noise and/or clutter background encountered. Because no single system can perform optimally for all possible backgrounds encountered, tradeoffs must be made between systems in terms of complexity, cost, performance in specified backgrounds, etc. For example, the tapped delay line mean level detector requires extremely accurate and broadbandwidth delay lines if implemented with analog circuitry. If implemented with digital circuitry, several digital numbers must be stored and added, thus requiring a large amount of equipment. The passive or active electronic filter must be very accurate and stable and thus can be a problem to implement and maintain. Finally, the distribution-free methods require many computations based on the input data such as ranking according to magnitudes.